The present invention relates to a method for the autonomous localization of a driverless motorized vehicle within a known environment using at least one sensor.
Methods of this type are known in a variety of designs from the related art. They serve to determine the position of a driverless motorized vehicle and by this, driverless navigation of the vehicle is enabled.
Localization methods of this type are used, for example, in the field of warehouse logistics. For the transport of loads in this domain, driverless, motorized vehicles are increasingly used in order to achieve a high level of automation.
Localization methods exist which make use of ‘artificial’ landmarks in the form of additional installations such as reflector markers, guide wires, radio stations or the like. These artificial landmarks are placed within the known environment in which the vehicle is to be localized such that, firstly, sufficient landmarks are present for reliable localization and, secondly, such that the associated equipment complexity and costs are kept as low as possible. As the sensor for detecting the artificial landmarks, for example, a range-measuring sensor in the form, for example, of a laser scanner can be used which is mounted on the vehicle and is pivoted evenly back and forth about a pivot axis using a sensor motor.
Autonomous localization methods, however, do not use artificial landmarks, but natural landmarks such as geometrical structural elements present in the environment in the form of tubes, beams, columns and the like. By this, a high degree of flexibility with highly accurate localization is achieved without impinging upon the environment. This has the advantage, in particular, that vehicle routes can be changed without any great financial or time cost. In this case also, a laser scanner which is mounted on the vehicle and is pivoted back and forth about a pivot axis can serve as the sensor.
Such autonomous localization methods function well provided sufficient environment information in the form of natural landmarks which can be detected with a suitable sensor are available. In practice, however, it often occurs that some environment regions have only few natural landmarks that can serve for localizing the vehicle. In such regions, it is therefore particularly important actually to detect and use the small amount of available information. However, the proper detection of landmarks by the sensor used can only be ensured through a suitably large measurement data density, for which a particular amount of time is required. Accordingly, the whole environment of the vehicle cannot be detected at once, but only gradually, with a corresponding chronological offset. This can have the effect that, due to the vehicle movement, some regions of the environment are not detected at all or only inadequately. In other words, it can occur that landmarks are passed by without being detected. In regions where sufficient landmarks are present, this is usually not problematic.
However, in regions where only a few landmarks exist, the non- detection of a landmark can have the result that the vehicle can no longer be localized, which leads to halting of the vehicle.